Liquid crystal display device

ABSTRACT

A liquid crystal display device in which the accuracy of the gap between its substrates can be improved includes a refelector formed in at least a part of each pixel area on a liquid-crystal-side surface of one of substrates disposed in opposition to each other with a liquid crystal interposed therebetween, the reflector serving to reflect light incident from the other substrate, an uneven portion formed on a reflection surface of the reflector, and columnar spacers formed on a liquid-crystal-side surface of the other substrate. Each of the columnar spacers is disposed with its vertex portion being opposed to a convex portion of the reflector.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device and,more particularly, to a liquid crystal display device which is called areflection type, a partially transparent type, or a slightly transparenttype.

2. Background Art

A liquid crystal display device has a pair of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, and a multiplicity of pixels are arranged in the spreadingdirection of the liquid crystal layer.

A unit for generating an electric field is formed in each of the pixelsso that the optical transmissivity of the liquid crystal is controlledby the electric field.

Accordingly, the liquid crystal display device needs light to betransmitted through each of the pixels, and such a liquid crystaldisplay device is known that which uses external light such as sunlightfor the purpose of reducing power consumption.

A liquid crystal display device called a reflection type is reflectexternal light transmitted through its liquid crystal layer from anobserver side to be totally reflected toward the observer side by meansof a reflector provided in each pixel. A liquid crystal display devicecalled a partly transparent type, a slightly transparent type or asemi-transparent type is provided a backlight in the liquid crystaldisplay device so that light from the backlight is transmitted through apart of each of the pixels and a reflector is formed in the remainingpart of each of the pixels so that external light from an observer sideis reflected.

Such a liquid crystal display device has a reflector provided in each ofthe pixels, and it is known that there is a liquid crystal displaydevice including ref lectors having uneven portions formed on theirentire reflection surfaces. In this liquid crystal display device, theuneven portions are used to produce scattering of reflected light toprevent mirror reflection, thereby preventing a problem such as areflection of the face of an observer in the display screen of thedevice.

SUMMARY OF THE INVENTION

However, in the liquid crystal display device constructed in thismanner, the unevenness of the uneven portion of each of the reflectorsappear directly on the liquid-crystal-side surface of a substrate onwhich the reflectors are formed.

Therefore, it has been pointed out that bead-shaped spacers for ensuringthe gap between the substrate and the other substrate disposed inopposition to each other with the liquid crystal layer interposedtherebetween are placed in convex portions or concave portions of thereflectors, so that the accuracy of the gap is degraded.

As a method of solving this problem, it is considered to increase thenumber of bead-shaped spacers. However, even this method cannot avoid aproblem which lowers the contrast of display.

The invention has been made in view of such a problem, and provides aliquid crystal display device in which the accuracy of the gap betweenits substrates is improved. Representative aspects of the inventiondisclosed in the present application will be described below in brief.

(1) A liquid crystal display device according to the invention includes,for example, a reflector formed in at least a part of each pixel area ona liquid-crystal-side surface of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, the reflector serving to reflect light incident from theother substrate, an uneven portion formed on a reflection surface of thereflector, and columnar spacers formed on a liquid-crystal-side surfaceof the other substrate. Each of the columnar spacers is disposed withits vertex portion being opposed to a convex portion of the reflector.

(2) A liquid crystal display device according to the invention includes,for example; a reflector formed in at least a part of each pixel area ona liquid-crystal-side surface of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, the reflector serving to reflect light incident from theother substrate, an uneven portion formed on a reflection surface of thereflector, and columnar spacers formed on a liquid-crystal-side surfaceof the other substrate. Each of the columnar spacers is disposed withits vertex portion being opposed to a convex portion of the reflectorand being not opposed to other convex portions adjacent to the convexportion.

(3) A liquid crystal display device according to the invention includes,for example, a plurality of gate signal lines disposed to be juxtaposedon a liquid-crystal-side surface of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, a plurality of drain signal lines disposed to bejuxtaposed to intersect the plurality of gate signal lines on theliquid-crystal-side surface of the one of the substrates, and pixelareas each of which is made of an area surrounded by adjacent ones ofthe plurality of gate, signal lines and adjacent ones of the pluralityof drain signal lines. Each of the pixel areas is provided with aswitching element to be operated by a scanning signal from a gate signalline and a pixel electrode to which an image signal from a drain signalline is supplied via the switching element. The pixel electrode has areflector function and is formed on an upper surface of a protectivefilm made of an organic material layer formed to cover the drain signalline and the switching element. A light scattering surface whichreflects unevenness of an uneven portion formed on the upper surface ofthe protective film is formed on a surface of the pixel electrode. Aninsulating film which is disposed to overlap the drain signal line andto be extended in a running direction of the drain signal line is formedin a layer underlying the protective film.

(4) A liquid crystal display device according to the invention includes,for example, a plurality of gate signal lines disposed to be juxtaposedon a liquid-crystal-side surface of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, a plurality of drain signal lines disposed to bejuxtaposed to intersect the plurality of gate signal lines on theliquid-crystal-side surface of the one of the substrates, and pixelareas each of which is made of an area surrounded by adjacent ones ofthe plurality of gate signal lines and adjacent ones of the plurality ofdrain signal lines. Each of the pixel areas is provided with a switchingelement to be operated by a scanning signal from a gate signal line anda pixel electrode to which an image signal from a drain signal line issupplied via the switching element. The pixel electrode has a reflectorfunction and is formed on an upper surface of a protective film made ofan organic material layer formed to cover the drain signal line and theswitching element. A light scattering surface which reflects unevennessof an uneven portion formed on the upper surface of the protective filmis formed on a surface of the pixel electrode. A convex portion formedon the protective film over the drain signal line is set to be larger infilm thickness than other convex portions.

(5) A liquid crystal display device according to the invention, forexample, presumes the construction described in (4), and columnarspacers are formed on a liquid-crystal-side surface of the othersubstrate and each of the columnar spacers is disposed with its vertexportion opposed to a part of the drain signal line.

(6) A liquid crystal display device according to the invention includes,for example, a reflector formed in at least a part of each pixel area ona liquid-crystal-side surf ace of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, the reflector serving to reflect light incident from theother substrate, and a light scattering surface formed on the uppersurface of the organic material layer, the light scattering surfacereflecting unevenness of an uneven portion formed on the upper surfaceof the organic material layer. The uneven portion formed on the uppersurface of the organic material layer is formed by etching withphotolithography techniques using a photomask having amounts of lighttransmission adjusted according to its contour lines.

(7) A liquid crystal display device according to the invention includes,for example, a reflector formed in at least a part of each pixel area ona liquid-crystal-side surface of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, the reflector serving to reflect light incident from theother substrate, an uneven portion formed on a reflection surface of thereflector, the reflector being provided close to a liquid crystal tosuch an extent that the liquid crystal is varied in layer thickness bythe uneven portion, and spacers interposed between the one and the otherof the substrates and made of bead-shaped spacers and columnar spacers.The columnar spacers are secured to the other substrate and each of thecolumnar spacers is disposed with its vertex portion opposed to a convexportion of the reflector.

(8) A liquid crystal display device according to the invention presumes,for example, the construction described in (7), and the columnar spacersare greater in number per one or more pixel areas than the bead-shapedspacers.

(9) A liquid crystal display device according to the invention presumes,for example, the construction described in (7), and each of thebead-shaped spacers has elasticity, and has a diameter set to be greaterthan a height of each of the columnar spacers.

(10) A liquid crystal display device according to the inventionincludes, for example, a reflector formed in at least a part of eachpixel area on a liquid-crystal-side surface of one of substratesdisposed in opposition to each other with a liquid crystal layerinterposed therebetween, the reflector serving to reflect light incidentfrom the other substrate, an uneven portion formed on a reflectionsurface of the reflector, the reflector being provided close to a liquidcrystal to such an extent that the liquid crystal is varied in layerthickness by the uneven portion, and spacers interposed between the oneand the other of the substrates and made of bead-shaped spacers andcolumnar spacers. The columnar spacers are secured to the othersubstrate and each of the columnar spacers is disposed with its vertexportion opposed to a convex portion of the reflector. At least one ofthe substrates is set to be less than 0.5 mm in thickness, and each ofthe bead-shaped spacers has elasticity and has a diameter set to begreater than a height of each of the columnar spacers.

(11) A liquid crystal display device according to the inventionincludes, for example, a reflector formed in at least a part of eachpixel area on a liquid-crystal-side surface of one of substratesdisposed in opposition to each other with a liquid crystal layerinterposed therebetween, the reflector serving to reflect light incidentfrom the other substrate, an uneven portion formed on a reflectionsurface of the reflector, the reflector being provided close to a liquidcrystal to such an extent that the liquid crystal is varied in layerthickness by the uneven portion, and spacers interposed between the oneand the other of the substrates and made of bead-shaped spacers andcolumnar spacers. The columnar spacers are secured to the othersubstrate and each of the columnar spacers is disposed with its vertexportion opposed to a convex portion of the reflector. At least one ofthe substrates is made of plastic or resin, and each of the bead-shapedspacers has elasticity and has a diameter set to be greater than aheight of each of the columnar spacers.

(12) A liquid crystal display device according to the inventionincludes, for example, a reflector formed in at least a part of eachpixel area on a liquid-crystal-side surface of one of substratesdisposed in opposition to each other with a liquid crystal layerinterposed therebetween, the reflector serving to reflect light incidentfrom the other substrate, an uneven portion formed on a reflectionsurface of the reflector, and columnar spacers formed on aliquid-crystal-side surface of the other substrate. Each of the columnarspacers being disposed with its vertex portion opposed to a convexportion of the reflector but not opposed to other convex portionsadjacent to the convex portion. A light-shielding film which overlapseach of the columnar spacer and covers a peripheral portion thereof isinterposed between each of the columnar spacers and the other substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more readily appreciated and understood fromthe following detailed description of preferred embodiments of theinvention when taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a cross-sectional view taken along line I-I of FIG. 3, showingone embodiment of the liquid crystal display device according to theinvention;

FIG. 2 is an equivalent circuit diagram showing one embodiment of theliquid crystal display device according to the invention;

FIG. 3 is a plan view showing one embodiment of a pixel area of theliquid crystal display device according to the invention;

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a plan view showing another embodiment of the pixel area ofthe liquid crystal display device according to the invention;

FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5;

FIGS. 7A and 7B are explanatory views showing the positionalrelationship between a columnar spacer and an uneven portion of a pixelelectrode in the liquid crystal display device according to theinvention;

FIG. 8 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the invention;

FIG. 9 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the invention;

FIG. 10 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the invention;

FIG. 11 is a process diagram showing one embodiment of a method ofmanufacturing a liquid crystal display device according to theinvention;

FIG. 12 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the invention; and

FIG. 13 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the invention

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the liquid crystal display device according to theinvention will be described below with reference to the accompanyingdrawings.

Embodiment 1.

<<Equivalent Circuit Diagram>>

FIG. 2 is an equivalent circuit diagram showing one embodiment of theliquid crystal display device according to the invention.

Referring to FIG. 2, a pair of transparent substrates SUB1 and SUB2 aredisposed to be opposed to each other with a liquid crystal layerinterposed therebetween, and the liquid crystal layer is sealed by asealing material SL which also serves to secure the transparentsubstrate SUB1 to the transparent substrate SUB2.

Gate signal lines GL and drain signal lines DL are formed on aliquid-crystal-side surface of the transparent substrate SUB1 in an areasurrounded by the sealing material SL. The gate signal lines GL aredisposed to be extended in the x direction and to be juxtaposed in the ydirection as viewed in FIG. 2, while the drain signal lines DL aredisposed to be extended in the y direction and to be juxtaposed in the xdirection as viewed in FIG. 2.

Areas each of which is surrounded by adjacent ones of the gate signallines GL and adjacent ones of the drain signal lines DL constitute pixelareas, respectively, and a matrix-formed aggregation of these pixelareas constitutes a liquid crystal display part AR.

A thin film transistor TFT and a pixel electrode PX are formed in eachof the pixel areas. The thin film transistor TFT is driven by a scanningsignal from one of the adjacent gate signal lines GL, and a video signalis supplied to the pixel electrode PX from one of the adjacent drainsignal lines DL via the thin film transistor TFT.

The pixel electrode PX is arranged to generate a voltage differencebetween the pixel electrode PX and a transparent counter electrode CTwhich is formed in common to each of the pixel areas on the transparentsubstrate SUB2, whereby the optical transmissivity of the liquid crystalis controlled by the voltage difference.

One end of each of the gate signal lines GL is formed to be extendedbeyond the sealing material SL, and the extended end constitutes aterminal to which an output terminal of a vertical scanning drivercircuit V is connected. Signals from a printed circuit board which isdisposed outside a liquid crystal display panel are inputted to inputterminals of the vertical scanning driver circuit V.

The vertical scanning driver circuit V is made of a plurality ofsemiconductor devices, and mutually adjacent ones of the gate signallines GL are grouped and one semiconductor device is assigned to eachgroup.

Similarly, one end of each of the drain signal lines DL is formed to beextended beyond the sealing material SL, and the extended endconstitutes a terminal to which an output terminal of a video signaldriver circuit He is connected. Signals from a printed circuit boardwhich is disposed outside the liquid crystal display panel are inputtedto input terminals of the video signal driver circuit He.

The video signal driver circuit He is made of a plurality ofsemiconductor devices, and mutually adjacent ones of the drain signallines DL are grouped and one semiconductor device is assigned to eachgroup.

Incidentally, the semiconductor devices used in the vertical scanningdriver circuit V and the video signal driver circuit He need notnecessarily be limited to those arranged in the above-described manner,and may also be, for example, semiconductor devices formed by a filmcarrier method. In addition, it goes without saying that the verticalscanning driver circuit V and the video signal driver circuit He mayalso be circuits formed directly on the surface of the transparentsubstrate SUB1.

Each one of the gate signal lines GL is sequentially selected by ascanning signal from the vertical scanning driver circuit V.

In addition, a video signal is supplied to each of the drain signallines DL by the video signal driver circuit He in synchronism with thetiming of selection of each one of the gate signal lines GL.

<<Construction of Pixel>>

FIG. 3 is a plan view showing the construction of the pixel area ofabove-described liquid crystal display device which is generally calleda reflection type. FIG. 1 is a cross-sectional view taken along line I-Iof FIG. 3, and FIG. 4 is a cross-sectional view taken along line IV-IVof FIG. 3.

As shown in FIG. 4, a pair of gate signal lines GL which are disposed tobe extended in the x direction and to be juxtaposed in the y directionare formed on the liquid-crystal-side surface of the transparentsubstrate SUB1.

These gate signal lines GL and a pair of drain signal lines DL whichwill be described later surround a rectangular area so that thisrectangular area is constructed as a pixel area.

An insulating film GI made of, for example, SiN is formed to cover thegate signal lines GL on the surface of the transparent substrate SUB1 onwhich the gate signal lines GL are formed in the above-described manner.

This insulating film GI has the function of an interlayer insulatingfilm between the gate signal lines GL and the drain signal lines DL (tobe described later) in an area in which the drain signal lines DL areformed, the function of a gate insulating film for a thin filmtransistor TFT (to be described later) in an area in which the thin filmtransistor TFT is formed, and the function of a dielectric film for acapacitance element Cadd (to be described later) in an area in which thecapacitance element Cadd is formed.

A semiconductor layer AS made of, for example, amorphous Si is formed ona surface of the insulating film GI in such a manner as to overlap apart of the gate signal line GL. Incidentally, it goes without sayingthat the material of the semiconductor layer AS need not necessarily belimited to amorphous Si and may also be, for example, poly-Si.

This semiconductor layer AS constitutes the semiconductor layer of thethin film transistor TFT, and a drain electrode SD1 and a sourceelectrode SD2 are formed on the upper surface of the semiconductor layerAS, thereby forming a reversed staggered structure MIS transistor whichuses a part of the gate signal line GL as its gate electrode. As amatter of course, a planar transistor may be used, particularly in thecase of poly-Si.

The drain electrode SD1 and the source electrode SD2 are formed at thesame time that the drain signal line DL is formed.

Specifically, the drain signal lines DL which are disposed to beextended in the y direction and to be juxtaposed in the x direction asviewed in FIG. 3 are formed, and a part of each of the drain signallines DL is formed to be extended onto the upper surface of thesemiconductor layer AS to form the drain electrode SD1. The sourceelectrode SD2 is formed to be spaced apart from the drain electrode SD1by a distance equivalent to the channel length of the thin filmtransistor TFT.

This source electrode SD2 is formed to be slightly extended from theupper surface of the semiconductor layer AS onto the upper surface ofthe insulating film GI within the pixel area, thereby forming a contactpart for providing connection to the pixel electrode PX which will bedescribed later.

Incidentally, a thin layer doped with high concentrations of impuritiesis formed at the interface between the semiconductor layer AS and eachof the source electrode SD2 and the drain electrode SD1. This layerfunctions as a contact layer.

This contact layer can be formed, for example, by the process of forminga high-concentration impurity layer on the surface of the semiconductorlayer AS at the same time as the formation of the semiconductor layerAS, and etching the impurity layer exposed from a mask formed by apattern made of the drain electrode SD1 and the source electrode SD2formed on the upper surface of the high-concentration impurity layer.

A protective film PSV which is made of, for example, SiN is formed onthe surface of the transparent substrate SUB1 on which the thin filmtransistors TFT, the drain signal lines DL, the drain electrodes SD1 andthe source electrodes SD2 are formed in the above-described manner. Thisprotective film PSV constitutes a layer for preventing direct contactbetween the thin film transistors TFT and the liquid crystal to preventcharacteristic degradation of the thin film transistors TFT.

This protective film PSV is made of a stacked structure in which aprotective film PSV1 formed by an inorganic material layer made of, forexample, SiN and an organic film PSV2 formed by an organic materiallayer made of, for example, resin film are stacked in that order.

In order that an uneven portion be formed on a surface of the protectivefilm PSV2, intermediate layers INTL are respectively formed at locationscorresponding to the convex portions of the uneven portion between theprotective film PSV2 and the protective film PSV1.

Each of these intermediate layers INTL is made of a material such as aresin, and is formed, for example, in a predetermined pattern byselective etching using so-called photolithography techniques.

The uneven portion is formed on the surface of the protective film PSV2which is formed to cover the intermediate layers INTL.

Pixel electrodes PX are formed on the upper surface of the protectivefilm PSV2. The pixel electrodes PX are made of, for example, an Al filmof good reflection efficiency.

Accordingly, the pixel electrodes PX also serve the function of areflector in the reflection type liquid crystal display device, and anuneven surface which reflects the unevenness of the surface of theprotective film PSV2 is formed on each of the pixel electrodes PX.

As described above, the uneven surface produces diffusion of reflectedlight to prevent mirror reflection, thereby preventing a problem such asa reflection of the face of an observer in the screen of the liquidcrystal display device.

As shown in FIG. 3, the pixel electrode PX is formed to occupy a certainpart of the pixel area, but to avoid the area in which the thin filmtransistor TFT is formed A part of the pixel electrode PX iselectrically connected to the source electrode SD2 of the thin filmtransistor TFT via a contact hole CH1 formed in a part of each of theprotective films PSV2 and PSV1.

Furthermore, a part of the pixel electrode PX is formed to be extendedto a location above the other adjacent gate signal line GL differentfrom the gate signal line GL which drives the thin film transistor TFT,thereby forming a portion which overlaps the other adjacent gate signalline GL. At that portion, a capacitance element Cadd which uses theprotective films PSV2 and PSV1 as its dielectric film is formed betweenthe pixel electrode PX and the other adjacent gate signal line GL.

This capacitance element Cadd has, for example, the function of causinga video signal supplied to the pixel electrode PX to be stored thereinfor a comparatively long time.

An alignment layer ORI1 is formed to cover the pixel electrodes PX onthe upper surface of the transparent substrate SUB1 on which the pixelelectrodes PX are formed in the above-described manner. The alignmentlayer ORI1 is a film which is in direct contact with the liquid crystal,and serves to determine the initial alignment direction of molecules ofthe liquid crystal by means of rubbing formed on the surface of thealignment layer ORI1.

As a matter of course, a non-rubbing method such as a vertical alignmentmethod may also be used.

Color filters FIL and the counter electrode CT which is formed oftransparent electrode, for example, ITO (Indium Tin Oxide) in common toeach of the pixel areas are formed in that order on theliquid-crystal-side surface of the transparent substrate SUB2 disposedto be opposed to the transparent substrate SUB1 constructed in theabove-described manner with the liquid crystal interposed therebetween.

Spacers SP for ensuring the gap between the transparent substrate SUB1and the transparent substrate SUB2 are fixedly formed on the transparentsubstrate SUB2. These spacers SP are made of columnar spacers fixed tothe transparent substrate SUB2, and are formed by subjecting a resinfilm applied to cover the counter electrode CT on the transparentsubstrate SUB2 to selective etching using photolithography techniques.

Therefore, the spacers SP can be accurately formed at the desiredlocations of each of the pixel areas by the desired number per pixelarea. Accordingly, in Embodiment 1, the spacers SP are formed so thattheir vertex portions are respectively disposed to be opposed to thedesired ones of the convex portions of the pixel electrodes PX.

Incidentally, an alignment film ORI2 is formed to cover the spacers SPon the liquid-crystal-side surface of the transparent substrate SUB2.

In the liquid crystal display device constructed in the above-describedmanner, since positions at which to form the respective spacers SP canbe defined during designing, it is possible to prevent thenon-uniformity of the gap between the opposed transparent substrates ofeach individual liquid crystal display device, and it is also possibleto reduce greatly the in-plane irregularity of such gap.

In particular, since the spacers SP are disposed to be opposed to thedesired ones of the convex portions of the pixel electrodes PX, it ispossible to decrease the height of the spacers SP required to ensure thenecessary layer thickness of the liquid crystal. Accordingly, during theformation of the spacers SP having a predetermined height, it ispossible to reduce the irregularity of the height.

Furthermore, in the case where each of the columnar spacers SP has ataper widened toward its fixed portion, it is possible to reduce thearea of its vertex portion as well as the area of the fixed portion.This fact contributes to an improvement in the aperture ratio per pixelarea.

Embodiment 2.

FIG. 5 is a plan view showing another embodiment of the pixel area ofthe liquid crystal display device according to the invention, andcorresponds to FIG. 3. FIG. 6 is a cross-sectional view taken along lineVI-VI of FIG. 5.

This liquid crystal display device is generally called asemi-transparent type. The construction shown in FIG. 5 differs fromthat shown in FIG. 1 in that an aperture is formed in an area of thepixel electrode PX which also serves as a reflector, in such a manner asto extend through the protective films PSV2 and PSV1 and the insulatingfilm GI all of which underlie the pixel electrode PX, and a pixelelectrode PX1 made of, for example, ITO (Indium Tin Oxide) is formed onthe surface of the transparent substrate SUB1 within the aperture.

Incidentally, an extended portion of the pixel electrode PX1 isconnected to the source electrode SD2 of the thin film transistor TFTvia a through-hole formed in the insulating film GI, whereby the pixelelectrode PX1 is kept at the same potential as the pixel electrode PX.

Even in this liquid crystal display device, similarly to the case shownin FIG. 1, the columnar spacer SP is formed on the transparent substrateSUB2, and the spacer SP is formed so that the vertex portion is disposedto avoid the area of the pixel electrode PX in which the aperture isformed, and to be opposed to any one of the convex portions of the pixelelectrode PX.

The liquid crystal display device having this construction can serve anadvantage similar to that of the liquid crystal display device shown inFIG. 1

Embodiment 3.

According to Embodiment 3, in the construction shown in each of FIGS. 3and 5 by way of example, the vertex portion of the spacer SP which isopposed to any one of the convex portions of the pixel electrode PX isdisposed so that the vertex portion is not opposed to other convexportions adjacent to the opposed convex portion.

As shown in FIG. 7A by way of example, in the case where the convexportions of the pixel electrode PX (in FIG. 7A, each of the vertexportions is denoted by “x”) are disposed at almost equal intervals ineach of the x and y directions, the spacer SP having a vertex portionopposed to one of the convex portions is disposed in such a manner asnot to be opposed to other convex portions which are adjacent to theopposed convex portion in the x and y directions, and the area of thevertex portion of the spacer SP is also set in the same manner.

As shown in FIG. 7B by way of example, in the case where the convexportions of the pixel electrode PX are formed in a wave-like shape, thespacer SP having a vertex portion opposed to one of the convex portions(in FIG. 7B, the vertex portion of each of the convex portions isdenoted by a straight line) is disposed in such a manner as not to beopposed to other convex portions which are adjacent to the opposedconvex portion. In addition, the area of the vertex portion of thespacer SP is set in the same manner.

The reason for this is to prevent degradation of gap accuracy whichoccurs when the vertex portion of the spacer SP is opposed to twoadjacent convex portions of the pixel electrode PX if both convexportions have different heights.

Incidentally, it goes without saying that the construction described inEmbodiment 3 can also be applied to other embodiments which will bedescribed below.

Embodiment 4.

FIG. 8 is a cross-sectional view showing another embodiment of the pixelarea of the liquid crystal display device according to the invention,and corresponds to FIG. 1.

The construction shown in FIG. 8 differs from that shown in FIG. 1 inthat an insulating layer INS which extends over the drain signal line DLin the running direction thereof and is, for example, wider than thedrain signal line DL is interposed between the protective film PSV1 andthe protective film PSV2.

The insulating layer INS can be formed of the same material and in thesame process as, for example, the intermediate layers INTL for formingthe uneven portion on the surface of the protective film PSV1.

In the liquid crystal display device constructed in this manner, sincethe distance between the drain signal line DL and the pixel electrode PXcan be made large by the insulating layer INS, it is possible to reducethe capacitance between the drain signal line DL and the pixel electrodePX, whereby it is possible to restrain the occurrence of luminanceirregularity or smears.

Embodiment 5.

FIG. 9 is a cross-sectional view showing another embodiment of the pixelarea of the liquid crystal display device according to the invention,and corresponds to FIG. 1.

The construction shown in FIG. 9 differs from that shown in FIG. 1 inthat a height W of the portion of the protective film PSV2 that overlapsthe drain signal line DL is made larger than the height of any of theconvex portions of an uneven portion formed on the protective film PSV2within the pixel area. In addition, the uneven portion is formed on thesurface of the protective film PSV2 without the intermediate layersINTL.

Even in the liquid crystal display device constructed in this manner,similarly to the case shown in FIG. 8, since the distance between thedrain signal line DL and the pixel electrode PX can be made large, it ispossible to reduce the capacitance between the drain signal line DL andthe pixel electrode PX.

The uneven portion formed on the surface of the protective film PSV2 inthe above-described manner is formed to have three different heightswith respect to the bottom surface of the protective film PSV2. A methodof forming this protective film PSV2 will be described later.

Embodiment 6.

FIG. 10 is a cross-sectional view showing another embodiment of thepixel area of the liquid crystal display device according to theinvention, and corresponds to FIG. 9.

Embodiment 6 presumes the construction shown in FIG. 6, and the spacerSP formed on the transparent substrate SUB2 is disposed so that thevertex portion is opposed to the drain signal line DL.

Specifically, the spacer SP is positioned at the highest portion of thesurface of the transparent substrate SUB1 within the pixel area, wherebythe height of the spacer SP can be reduced.

Embodiment 7.

FIG. 11 is a view showing the process of one embodiment of a method ofmanufacturing a liquid crystal display device according to theinvention.

FIG. 11 shows a method of forming the protective film PSV2 whose surfacehas an uneven portion having three different heights with respect to thebottom surface in each of the constructions shown in FIGS. 9 and 10.

Step 1 (FIG. 11A)

The transparent substrate SUB1 having a liquid-crystal-side surface onwhich the insulating film GI and the protective film PSV1 are formed isprepared.

Step 2 (FIG. 11B)

An organic material layer is formed by application on the surface of theprotective film PSV1 of the transparent substrate SUB1, whereby theprotective film PSV2 is formed on the surface of the protective filmPSV1. In Step 2 of this embodiment, the material of the organic materiallayer is selected from among photocuring materials havingphotosensitivity like that of so-called photoresist.

The surface of the protective film PSV2 is formed to be comparativelyflat.

Step 3 (FIG. 11C)

The surface of the protective film PSV2 is sensitized by selectiveexposure using a photomask PM.

In this case, the photomask PM is made high in transparency in portionscorresponding to individual areas on the surface of the protective filmPSV2 in each of which a convex portion is to be formed, and is made highin opaqueness in portions corresponding to individual areas on thesurface of the protective film PSV2 in each of which a concave portionis to be formed.

The photomask PM is formed to vary smoothly from transparency toopaqueness in a region which extends from a portion corresponding toeach of the areas in which the respective convex portions are to beformed to a portion corresponding to an adjacent one of the areas inwhich the respective concave portions are to be formed.

In addition, since the portion of the protective film PSV2 that overlapsthe drain signal line DL formed on the transparent substrate SUB1 is tobe formed into the highest convex portion within the pixel area, thetransparency of the photomask PM needs to be made higher in an areacorresponding to the highest convex portion than in areas correspondingto the other convex portions.

In the case where the opaqueness and transparency of this photomask PMare to be made different in degree, it is desirable that the amount oflight to be transmitted through the photomask PM can be adjusted on alocation-by-location basis. A specific construction may be such that aplurality of juxtaposed slits are formed in an opaque film formed on thephotomask PM to adjust the amount of light with the width of each of theslit or such that an opaque film whose film thickness can be varied tovary the amount of light to be transmit ted therethrough is formed onthe photomask PM to adjust the amount of light to be transmitted throughthe photomask PM.

It goes without saying that the material of the protective film PSV2need not necessarily be limited to the photocuring material and aphotodegradable material may also be used. In this case, the transparentareas and the opaque areas of the photomask PM are formed to have thereverse relationship.

Step 4 (FIG. 11D)

After the completion of selective exposure whose exposure amount differsin degree on a location-by-location basis, the protective film PSV2 isdeveloped, whereby an uneven portion is formed on the surface of theprotective film PSV2.

Embodiment 8.

FIG. 12 is a cross-sectional view showing another embodiment of thepixel area of the liquid crystal display device according to theinvention, and corresponds to FIG. 8.

The construction shown in FIG. 12 differs from that shown in FIG. 8 inthat spacers for ensuring the gap between the transparent substrate SUB1and the transparent substrate SUB2 use not only the columnar spacers SPbut also bead-shaped spacers SP1.

In the case where the columnar spacers SP are used as such spacers, thegap between the transparent substrate SUB1 and the transparent substrateSUB2 can be controlled with high accuracy, and the gap can also be madenarrow. However, there is a risk that the columnar spacers SP may bedestroyed when external force is applied to either of the transparentsubstrates SUB1 or SUB2.

The bead-shaped spacers SP1 are intended to solve this problem, andoriginally are not used for ensuring the gap between the transparentsubstrate SUB1 and the transparent substrate SUB2. Accordingly, thediameter of each of the bead-shaped spacers SP1 may be smaller than thesize of the desired gap (for example, 3 μm).

In addition, it is preferable that the number of the bead-shaped spacersSPI per unit area be greater than the number of the columnar spacers SPper unit area.

Specifically, it is preferable to form two or more bead-shaped spacersSP1 per pixel with respect to one columnar spacer SP per pixel, or oneor more bead-shaped spacers SP1 per pixel with respect to one columnarspacer SP per plural pixels. Otherwise, it is preferable to form pixelsso that the number of pixels in which the bead-shaped spacers SP1 existbecomes greater than the number of pixels in which the columnar spacersSP exist.

Although in the above description it has been stated that the diameterof each of the bead-shaped spacers SP1 may be comparatively small, thediameter of each of the bead-shaped spacers SP1 may be larger than theheight of each of the columnar spacers SP. In this case, by forming thebead-shaped spacers SP1 from a material having elasticity, thebead-shaped spacers SP1 can function as effective spacers together withthe columnar spacers SP.

Embodiment 9.

In Embodiment 9, at least one of the transparent substrates SUB1 andSUB2 is made of a glass substrate of less than 0.5 mm in thickness onthe premise that the spacers for ensuring the gap between thetransparent substrate SUB1 and the transparent substrate SUB2 arerealized by the columnar spacers SP and the bead-shaped spacers SPI.

In the case where the glass substrate of less than 0.5 mm in thicknessis used, deformation increases owing to external force applied to theglass substrate, but the gap is ensured by the spacers describedpreviously in at least any of Embodiments 1 to 8.

For the same reason, it goes without saying that at least one of thetransparent substrates SUB1 and SUB2 may be made of plastic or resin.

Embodiment 10.

FIG. 13 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the invention, andcorresponds to FIG. 8.

The construction shown in FIG. 13 differs from that shown in FIG. 8 inthat each columnar spacer SP is formed on the transparent substrate SUB2in such a manner that a light-shielding film BM which overlaps thecolumnar spacer SP and covers the peripheral portion thereof isinterposed at the position of the fixed portion of the columnar spacerSP.

The light-shielding film BM is provided for preventing light leak due tothe columnar spacer SP formed to have a volume larger than that of thebead-shaped spacer SP1.

The light-shielding film BM is formed between, for example, thetransparent substrate SUB2 and the color filter FIL, and is formed of,for example, a resin containing a black pigment.

Incidentally, it goes without saying that although in Embodiment 10 thelight-shielding film BM is formed on the transparent substrate SUB2, thelight-shielding film BM may also be formed on the transparent substrateSUB1.

As a matter of course, such light-shielding film BM can be applied toeach of the above-described embodiments.

As is apparent from the foregoing description, in accordance with theliquid crystal display device according to the invention, it is possibleto improve the accuracy of the gap between the substrates.

1. A liquid crystal display device comprising: a reflector formed in atleast a part of each pixel area on a liquid-crystal-side surface of oneof substrates disposed in opposition to each other with a liquid crystallayer interposed therebetween, the reflector serving to reflect lightincident from the other substrate; an uneven portion formed on areflection surface of the reflector; and columnar spacers formed on aliquid-crystal-side surface of the other substrate, each of the columnarspacers being disposed with its vertex portion being opposed to a convexportion of the reflector.
 2. A liquid crystal display device comprising:a plurality of gate signal lines disposed to be juxtaposed on aliquid-crystal-side surface of one of substrates disposed in oppositionto each other with a liquid crystal layer interposed therebetween; aplurality of drain signal lines disposed to be juxtaposed to intersectthe plurality of gate signal lines on the liquid-crystal-side surface ofthe one of the substrates; and pixel areas each of which is made of anarea surrounded by adjacent ones of the plurality of gate signal linesand adjacent ones of the plurality of drain signal lines, each of thepixel areas being provided with a switching element to be operated by ascanning signal from a gate signal line and a pixel electrode to whichan image signal from a drain signal line is supplied via the switchingelement, the pixel electrode having a reflector function and beingformed on an upper surface of a protective film made of an organicmaterial layer formed to cover the drain signal line and the switchingelement, a light scattering surface which reflects unevenness of anuneven portion formed on the upper surface of the protective film beingformed on a surface of the pixel electrode, an insulating film which isdisposed to overlap the drain signal line and to be extended in arunning direction of the drain signal line being formed in a layerunderlying the protective film.
 3. A liquid crystal display devicecomprising: a reflector formed in at least a part of each pixel area ona liquid-crystal-side surface of one of substrates disposed inopposition to each other with a liquid crystal layer interposedtherebetween, the reflector serving to reflect light incident from theother substrate; and a light scattering surface formed on the uppersurface of the organic material layer, the light scattering surfacereflecting unevenness of an uneven portion formed on the upper surfaceof the organic material layer, the uneven portion formed on the uppersurface of the organic material layer being formed by etching withphotolithography techniques using a photomask having amounts of lighttransmission adjusted according to its contour lines.